A Study Of Voltage Control Partitioning Method For Power Network With Wind Farms

With the power system expanded, the voltage stability problem becomes increasingly prominent caused by the large connected regional system, power to the load center with long-distance, high-power transmission and other factors. Voltage unstability makes huge negative impact to the social and economic. So the effective control of voltage stability has been growing concerned. However, modern power industry's main features: large-scale systems interconnected, complex structures have become a largest resistance to the power system stability analysis. It is feasible and necessary to divide the power grid into several regions for safety and stability analysis, monitoring and control. This helps to shorten the time of stability analysis and improve computational efficiency. It also can increase economic efficiency by reducing investment of equipment and capital. In various voltage monitoring programs, the classification voltage control scheme is a good solution, which is invented by the EDF, has been applied in France, Italy, Spain, Belgium and other countries. The scheme divides the power network into several decoupling areas in space to monitor, and the net voltage control is divided into three levels according to the control time. The first level of voltage controlling is set in the power plant, whose control time limits in seconds; The secondary voltage controlling is set in the pivotal point in the power network, which the control time constant is about tens of seconds to minutes; The third voltage controlling is set in the system dispatch center, which the control time constant is generally ten minutes to several hours. Voltage control partitioning method ,which this paper studed, is mainly used in secondary voltage control.In recent years, wind power has rapidly developed in China which especially in some resource-rich provinces of wind power, wind power has been or will soon become an important part of power supply. However, system voltage stability's challenges will become serious with the development of its large-scale due to the randomness, intermittent, non-schedulability of wind power output. Currently, the power system voltage partitioning monitoring research , which considers the factor of wind power, is still relatively rare. So, it needs to consider that wether the existed partitioning method could considerding the wind farm factor and how to improve. The way to deal with wind farm node in power flow calculation, the influence of adding wind power node into the system, the reasonableness of partitioning result and its suitable scope all need to be researched. Based on this, this paper discretes the probability distribution of wind power output into scenes. This paper proposed a method to selecte the most representative expected-scene; proposed and calculated the expected-scene's full-dimensional voltage/reactive power sensitivity containning richer information matrix, which draws basic idea of reactive power source control space; used the fuzzy clustering approach based on transitive closure comprehensive analyzed a feasible voltage control partitioning method for a power grid including wind farm.